High-speed heat and pressure belt fuser

Abstract

A high speed heat and pressure belt fuser apparatus or structure for fixing toner images including an endless belt and a pair of pressure members between which the endless belt is sandwiched for forming a fusing nip through which substrates carrying toner images pass with the toner images contacting an outer surface of the endless belt. Thus, one of the pressure rolls is supported internally of the endless belt while the other pressure roll is supported externally of the belt. The belt has at least one conformable or deformable layer which cooperates with a deformable or conformable layer on at least one of the pressure members to provide a large nip that yields high gloss images, long belt life, minimal edge wear and reliable stripping at high speeds. Effective substrate stripping is accomplished by wrapping a portion of the belt about the external roll in a post-nip area.

What is claimed is:  
     
       1. A high-speed heat and pressure belt fuser structure, said belt fuser structure comprising: 
       an endless belt comprising at least one conformable layer;  
       a plurality of rolls positioned internally of said belt for supporting movement of said belt in an endless path, one of said rolls comprising an internal pressure roll contacting an inner surface of said belt;  
       an external pressure roll supported for contact with an outer surface of said belt such that said belt is sandwiched between said internal and external pressure rolls, one of said pressure rolls including at least one conformable layer;  
       an external source of thermal energy for elevating the surface temperature in a pre-nip area of said belt  
       means for effecting pressure engagement of said rolls whereby an elongated nip is formed through which imaged substrates pass with toner images carried thereby contacting said outer surface of said belt;  
       said conformable layers having a combined thickness and hardness that provides said elongated nip for fusing said toner images with minimal gloss degradation and belt edge wear and without causing premature belt failure;  
       said belt and one of said pressure members cooperating in a post-nip area for effecting stripping of said substrates; and  
       said at least one conformable layer of said endless belt having a thickness in order of 3 to 5 mm and said at least one conformable layer of said one of said pressure rolls having a thickness in the order of 10 to 15 mm.  
     
     
       2. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein said one of said pressure rolls comprising a conformable layer is disposed internally of said belt such that it contacts an inner surface of said belt. 
     
     
       3. A high-speed heat and pressure belt fuser structure according to  claim 2  wherein said one of said pressure members comprises one of said rolls supporting said belt for movement. 
     
     
       4. A high-speed heat and pressure belt fuser structure according to  claim 2  wherein one of said rolls for supporting said belt for movement is positioned for enabling said belt to cooperate with said one of said pressure members for effecting stripping of said substrates. 
     
     
       5. A high-speed heat and pressure belt fuser structure according to  claim 4  wherein said roll that is positioned for cooperating with said one of said pressure members for effecting stripping of said substrates is supported beyond said post-nip area whereby a portion of said belt is wrapped about said pressure roll contacting said outer surface of said belt to compress the surface of the belt in that area thus decreasing the belt speed compared to a non-wrapped or IPR wrapped belt in the post-nip area so that there is sufficient creep to effect stripping of imaged substrate. 
     
     
       6. A high-speed heat and pressure belt fuser structure according to  claim 4  wherein said belt has a thickness in the order of 3 to 5 mm and said at least one conformable layer of said one of said pressure rolls has a thickness in the order of 10 to 20 mm. 
     
     
       7. A high-speed heat and pressure belt fuser structure according to  claim 6  wherein said conformable layers have a ShoreA hardness in the order of 35 to 80. 
     
     
       8. A high-speed heat and pressure belt fuser structure according to  claim 7  wherein said nip has a length in the order of 19 to 21 mm. 
     
     
       9. A high-speed heat and pressure belt fuser structure according to  claim 8  wherein said nip has a creep in the order of −2 to +2%. 
     
     
       10. A high-speed heat and pressure belt fuser structure according to  claim 9  wherein a pressure of about 80 psi is applied between said pressure rolls for forming said elongated nip. 
     
     
       11. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein said one of said pressure members comprises one of said rolls supporting said belt for movement. 
     
     
       12. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein one of said rolls for supporting said belt for movement is positioned for enabling said belt to cooperate with said one of said pressure members for effecting stripping of said substrates. 
     
     
       13. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein said conformable layers have a ShoreA hardness in the order of 35 to 80. 
     
     
       14. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein said nip has a length of about 19 to 20 mm. 
     
     
       15. A high-speed heat and pressure belt fuser structure according to  claim 14  herein a pressure of about 80 psi is applied between said pressure rolls for forming said elongated nip. 
     
     
       16. A high-speed heat and pressure belt fuser structure according to  claim 1  wherein said nip has a creep in the order of −2 to +2%.